A thermistor is a sintered body made up of specific metal oxides which shows a change in electrical resistance depending on temperature change. Thermistor devices comprising this sintered body and a pair of electrode have been widely employed in detecting temperature in various fields, for example, the temperature of integrated circuits, the temperature of automotive gas emissions, the flame temperature of gas water heaters and so on.
It is required that a sintered body for thermistor devices employed in these thermistor devices for detecting temperature shows (1) a small constant B, (2) a small change in resistance to a heat profile, and (3) a little scatter in resistance. The constant B as used herein is a constant serving as an indication of a change in electrical resistance. A smaller constant B means the smaller change in electrical resistance depending on temperature change. A thermistor device (a sintered body for thermistor devices) satisfying the performance requirements as described above has a wide detection temperature range, a favorable heat resistance and a high temperature detection accuracy.
As such a sintered boy for thermistor devices, there has been known one comprising (Y, Sr) (Cr, Fe, Ti)O3 as the main component (see JP-A-7-201526). This sintered body for thermistor devices shows electrical resistances of about 100 kΩ and about 80 kΩ respectively at 300° C. and 900° C. It is an excellent sintered body for thermistor devices which has a constant B of about 8000 K at 300 to 900° C. and remains stable to a heat profile within a temperature range of from 300 to 1000° C. There have been also known a sintered body for thermistor devices comprising Y (Cr, Mn) O3+Y2O3 as the main component (see JP-A-2002-124403) and a sintered body for thermistor devices comprising (Y, Ca) CrO3+0.5YAlO3 as the main component (see JP-A-6-338402).